Implement alpha_blend for YUV420P and YUV420P10. Improve unit test.

[dcpomatic.git] / src / lib / image.cc

diff --git a/src/lib/image.cc b/src/lib/image.cc
index d1f1fb9d14702873db816e8ef0ef45b8bd8b710e..2511df73ea87bed9638df60e324ea77a0bc24557 100644 (file)
--- a/src/lib/image.cc
+++ b/src/lib/image.cc
@@ -51,7 +51,7 @@ using boost::shared_ptr;
 using dcp::Size;
 
 int
-Image::line_factor (int n) const
+Image::vertical_factor (int n) const
 {
        if (n == 0) {
                return 1;
@@ -65,11 +65,8 @@ Image::line_factor (int n) const
        return pow (2.0f, d->log2_chroma_h);
 }
 
-/** @param n Component index.
- *  @return Number of samples (i.e. pixels, unless sub-sampled) in each direction for this component.
- */
-dcp::Size
-Image::sample_size (int n) const
+int
+Image::horizontal_factor (int n) const
 {
        int horizontal_factor = 1;
        if (n > 0) {
@@ -79,10 +76,18 @@ Image::sample_size (int n) const
                }
                horizontal_factor = pow (2.0f, d->log2_chroma_w);
        }
+       return horizontal_factor;
+}
 
+/** @param n Component index.
+ *  @return Number of samples (i.e. pixels, unless sub-sampled) in each direction for this component.
+ */
+dcp::Size
+Image::sample_size (int n) const
+{
        return dcp::Size (
-               lrint (ceil (static_cast<double>(size().width) / horizontal_factor)),
-               lrint (ceil (static_cast<double>(size().height) / line_factor (n)))
+               lrint (ceil (static_cast<double>(size().width) / horizontal_factor (n))),
+               lrint (ceil (static_cast<double>(size().height) / vertical_factor (n)))
                );
 }
 
@@ -191,7 +196,7 @@ Image::crop_scale_window (
                   we've cropped all of its Y-channel pixels.
                */
                int const x = lrintf (bytes_per_pixel(c) * crop.left) & ~ ((int) desc->log2_chroma_w);
-               scale_in_data[c] = data()[c] + x + stride()[c] * (crop.top / line_factor(c));
+               scale_in_data[c] = data()[c] + x + stride()[c] * (crop.top / vertical_factor(c));
        }
 
        /* Corner of the image within out_size */
@@ -541,6 +546,39 @@ Image::alpha_blend (shared_ptr<const Image> other, Position<int> position)
                }
                break;
        }
+       case AV_PIX_FMT_YUV420P:
+       case AV_PIX_FMT_YUV420P10:
+       {
+               shared_ptr<Image> yuv = other->scale (other->size(), dcp::YUV_TO_RGB_REC709, _pixel_format, false, false);
+
+               for (int i = 0; i < 3; ++i) {
+                       dcp::Size const tsize = sample_size(i);
+                       dcp::Size const osize = yuv->sample_size(i);
+                       int const tbpp = ceil (bytes_per_pixel(i) / horizontal_factor(i));
+                       int const obpp = ceil (yuv->bytes_per_pixel(i) / yuv->horizontal_factor(i));
+                       int const abpp = other->bytes_per_pixel(0);
+                       start_tx /= horizontal_factor (i);
+                       start_ty /= vertical_factor (i);
+                       start_ox /= yuv->horizontal_factor (i);
+                       start_oy /= yuv->vertical_factor (i);
+                       for (int ty = start_ty, oy = start_oy; ty < tsize.height && oy < osize.height; ++ty, ++oy) {
+                               /* this image */
+                               uint8_t* tp = data()[i] + ty * stride()[i] + start_tx * tbpp;
+                               /* overlay image */
+                               uint8_t* op = yuv->data()[i] + oy * yuv->stride()[i];
+                               /* original RGBA for alpha channel */
+                               uint8_t* ap = other->data()[0] + oy * other->stride()[0];
+                               for (int tx = start_tx, ox = start_ox; tx < tsize.width && ox < osize.width; ++tx, ++ox) {
+                                       float const alpha = float (ap[3]) / 255;
+                                       *tp = *op * alpha + *tp * (1 - alpha);
+                                       tp += tbpp;
+                                       op += obpp;
+                                       ap += abpp;
+                               }
+                       }
+               }
+               break;
+       }
        default:
                throw PixelFormatError ("alpha_blend()", _pixel_format);
        }